In commonly-assigned application Ser. No. 07/771,346, filed Oct. 4, 1991, a musical display such as a Christmas display is provided comprising a plurality of ornaments. Each of the plurality of ornaments includes a pair of bells, wherein each bell is capable of playing a distinctive note or tone. Each ornament also includes a striker for striking, one at a time, a selected one of the pair of bells. An electronic controller is provided for generating electrical sights to each ornament to strike each bell in coordination and, thus, playing a musical tune.
Such a Christmas display is fabricated from bells which are mass-produced and are low-cost. These low-cost bells typically deviate from their respective nominal or ideal tones by, for example, up to five percent. However, in such an apparatus, in order to produce a pleasing musical tune, all of the bells must be in tune, that is, each bell must accurately emit its respective nominal note. Otherwise, if such a Christmas display comprises bells which have tonal characteristics that deviate from their respective nominal tones, the musical Christmas display will sound "off-key" or out of tune and not very pleasing to the listener.
To avoid the above-discussed disadvantages, manufacturing techniques include the use of suitable testing equipment known in the art, such as digital frequency meters, oscilloscopes, etc., to measure the note or, more specifically, the frequency characteristic of each bell. If the tested bell has a frequency characteristic within a predetermined tolerance of its nominal frequency, the bell is used; otherwise, the bell is discarded.
This manufacturing technique has several disadvantages. First, the testing equipment is rather complex, costly, and time-consuming to use. And due to its complexity, operators of such equipment must have a higher skill than is generally required for the manufacture of such Christmas ornaments. Therefore this technique does not lend itself well to low cost mass-produced products. Second, such test equipment typically indicates the absolute tonal characteristic. That is, the test equipment will display the fundamental frequency of the bell. Therefore, the operator must interpret these results to determine whether the bell is acceptable or not. Such interpretations could lead to inconsistent and/or inaccurate determinations, especially for those operators who are not familiar with the test equipment. Moreover, bells having frequencies outside the acceptable tolerance of nominal frequencies are generally discarded. This results in discarding many bells, generally raising manufacturing costs.
The inventors recognize that a reasonable rendition of a musical tune can be produced if the bells used in the display are in tune relative to one another. In other words, if each bell emits a note which is, by way of example, 2% higher than its respective nominal note, the playing of such device will produce a pleasing musical tune or melody, even with bells that would have been discarded by using conventional manufacturing techniques.
Therefore, the inventors propose an inexpensive device which is simple to use and can simply grade the bells with respect to deviation from their respective nominal notes. In such a manufacturing technique, the bells are first graded according to their deviation from their respective nominal notes. The display is then assembled from bells of the various nominal notes having the same grade. Accordingly, with such a technique fewer bells are discarded resulting in a higher utilization rate of the bells. Therefore, manufacturing costs may be reduced.